Power converter and synchronous-asynchronous mode control

Abstract

An apparatus includes a controller (such as associated with a power converter). The controller is operative to receive input control settings. Based on the input control settings, the controller controls a magnitude of an output current generated by the power converter. The output current from the power converter powers light emitting hardware. The controller transitions between operating the power converter in an asynchronous mode and a synchronous mode to produce the output current.

The invention claimed is: 
     
       1. An apparatus comprising:
 a controller operative to:
 receive control input indicating output current settings in which to control a power converter; 
 control a magnitude of an output current generated by the power converter as specified by the control input, the output current from the power converter operative to power light emitting hardware; 
 transition between operating the power converter in an asynchronous mode and a synchronous mode to produce the output current; and 
 wherein the power converter includes low-side switch circuitry and a diode component disposed in parallel, the controller operative to switch the low side switch circuitry ON and OFF in each control cycle during operation of the power converter in the synchronous mode, the controller operative to continuously deactivate the low side switch circuitry during control cycles while the power converter is operated in the asynchronous mode. 
 
 
     
     
       2. The apparatus as in  claim 1 , wherein the controller is operative to control switching of the power converter in accordance with the asynchronous mode during conditions in which the control input indicates to generate the magnitude of the output current supplied to the light emitting hardware to be above a threshold level. 
     
     
       3. The apparatus as in  claim 1 , wherein the controller is operative to control switching of the power converter in accordance with the synchronous mode during conditions in which the control input indicates to produce the magnitude of the output current supplied to the light emitting hardware to be below a threshold level. 
     
     
       4. The apparatus as in  claim 3 , wherein the synchronous mode is a forced continuous conduction mode in which current through a respective inductor of the power converter reverses direction during a respective control cycle to power the light emitting hardware. 
     
     
       5. The apparatus as in  claim 1 , wherein the operation in the asynchronous mode includes implementation of high side switch circuitry and the diode component in the power converter to produce the output current. 
     
     
       6. The apparatus as in  claim 1 , wherein the operation in the synchronous mode includes implementation of switching between activating high side switch circuitry and the low side switch circuitry in the power converter to produce the output current. 
     
     
       7. The apparatus as in  claim 1 , wherein the controller is further operative to transition the power converter from operating in the asynchronous mode and the synchronous mode depending on a magnitude of the output current as specified by the control input. 
     
     
       8. The apparatus as in  claim 1 , wherein the controller is further operative to transition the power converter from operating in the asynchronous mode to the synchronous mode in response to a change of the control input from a first setting to a second setting, the second setting indicating to reduce a magnitude of light output from the light emitting hardware with respect to the first setting. 
     
     
       9. The apparatus as in  claim 1 , wherein the controller is further operative to transition the power converter from operating in the synchronous mode to the asynchronous mode in response to a change of the control input from a first setting to a second setting, the second setting indicating to increase a magnitude of light output from the light emitting hardware with respect to the first setting. 
     
     
       10. The apparatus as in  claim 1 , wherein the power converter includes an inductor operative to supply the output current to the light emitting hardware; and
 wherein the synchronous mode is a forced continuous conduction mode in which the output current flows in a forward direction and reverse direction at different times through the inductor during a respective control cycle of operating the power converter. 
 
     
     
       11. The apparatus as in  claim 1 , wherein the controller is further operative to implement hysteretic mode transitions between operation in the asynchronous mode and operation in the synchronous mode. 
     
     
       12. The apparatus as in  claim 1 , wherein the controller is operative to switch the low side switch circuitry ON and OFF in a respective control cycle during operation of the power converter in the asynchronous mode in which the output current includes first current supplied though the diode component and second current supplied through the low side switch circuitry, a magnitude of the first current being greater than a magnitude of the second current during the asynchronous mode, the diode component disparately located with respect to the low side switch circuitry. 
     
     
       13. The apparatus as in  claim 1 , wherein the controller is operative to transition from operating the power converter in the asynchronous mode to operating the power converter in the synchronous mode to produce the output current depending on the magnitude of the output current. 
     
     
       14. The apparatus as in  claim 1 , wherein the low side switch circuitry includes an inherent diode; and
 wherein the diode component is a separate component with respect to the low side switch circuitry and is disposed in parallel with the inherent diode of the low side switch circuitry. 
 
     
     
       15. The apparatus as in  claim 1  further comprising:
 an inductor coupled to the low side switch circuitry and the diode component; 
 wherein the low side switch circuitry supplies first current through the inductor during the synchronous mode to produce the output current; and 
 wherein the diode component supplies second current through the inductor during the asynchronous mode to produce the output current. 
 
     
     
       16. The apparatus as in  claim 1 , wherein the controller is further operative to transition the power converter between operation of the power converter in the asynchronous mode and the synchronous mode depending on a magnitude setting of the output current as specified by the control input. 
     
     
       17. The apparatus as in  claim 1 , wherein the synchronous mode is a mode in which current flows in both directions through a respective inductor of the power converter during each respective control cycle of multiple control cycles, the current through the inductor producing the output current to power the light emitting hardware. 
     
     
       18. The apparatus as in  claim 1 , wherein the output current generated by the power converter is supplied from an inductor of the power converter through a series combination of the light emitting hardware and a resistor component; and
 wherein the controller is operative to receive feedback from a node coupling the light emitting hardware to the resistor component, the feedback indicating a magnitude of the output current. 
 
     
     
       19. The apparatus as in  claim 18 , wherein the controller is further operative to:
 compare the feedback to a threshold level derived from the control input; and 
 regulate the magnitude of the output current with respect to the threshold level, the output current supplied to a combination of the light emitting hardware and capacitor disposed in parallel with the light emitting hardware. 
 
     
     
       20. A method comprising:
 receiving control input indicating output current control settings of a power converter; 
 controlling a magnitude of an output current generated by the power converter as specified by the control input, the output current from the power converter operative to power light emitting hardware; 
 transitioning between operating the power converter in an asynchronous mode and a synchronous mode to produce the output current; and 
 wherein the power converter includes low-side switch circuitry and a diode component disposed in parallel, the method further comprising:
 switching the low side switch circuitry ON and OFF in each control cycle during operation of the power converter in the synchronous mode; and 
 continuously deactivating the low side switch circuitry during control cycles of operating the power converter in the asynchronous mode. 
 
 
     
     
       21. The method as in  claim 20  further comprising:
 switching high side switch circuitry in the power converter in accordance with the asynchronous mode during conditions in which the control input indicates to provide power to the light emitting hardware above a threshold level. 
 
     
     
       22. The method as in  claim 20  further comprising:
 switching high side switch circuitry and the low side switch circuitry of the power converter in accordance with the synchronous mode during conditions in which the control input indicates to provide power to the light emitting hardware below a threshold level. 
 
     
     
       23. The method as in  claim 22 , wherein the synchronous mode is a forced continuous conduction mode. 
     
     
       24. The method as in  claim 20 , wherein the operation of the power converter in the asynchronous mode includes implementation of high side switch circuitry and the diode component in the power converter to produce the output current. 
     
     
       25. An apparatus comprising:
 a controller operative to:
 receive control input indicating output current settings in which to control a power converter; 
 control a magnitude of an output current generated by the power converter as specified by the control input, the output current from the power converter operative to power light emitting hardware; and 
 transition between operating the power converter in an asynchronous mode and a synchronous mode to produce the output current; 
 
 wherein the controller is further operative to:
 monitor the magnitude of the output current, the output current supplied to a combination of the light emitting hardware and a capacitor disposed in parallel with the light emitting hardware; and 
 regulate the magnitude of the output current from the power converter with respect to an output current value as specified by the control input. 
 
 
     
     
       26. The apparatus as in  claim 25 , wherein the controller is further operative to regulate the magnitude of the output current based on peaks of the monitored magnitude of the output current.